For example, a mechanism is provided for moving a seating surface for a vehicle up and down via a link. In association with the mechanism, a load detecting device for a vehicle seat, which measures load applied to the seat for the vehicle, is used as follows. The device is used for controlling an airbag. For example, the airbag is switched on and off according to the detected load value. Many of the load detecting devices for the vehicle seat use a load cell. The load cell measures an amount of strain generated at a censor strain portion and detects the load based on the measurement of the amount of strain.
Conventionally, with regard to the above-mentioned load detecting device for the vehicle seat, a device provided with a deflection controlling mechanism is proposed. The deflection controlling mechanism directly restrains a strain generated at the sensor strain portion against an excessive load that is applied to the sensor strain portion during the impact of the vehicle. For example, refer to JP 3683712. The mechanism is provided as a preventing means for deforming the strain portion when a large load exceeding a predetermined value is applied. For example, the mechanism is composed of a control bar connected to a lower surface of seat rails and a control block formed on a seat fixed portion.
However, the above-mentioned deflection controlling mechanism is able to prevent the deformation of the sensor strain portion when the excessive load such as the one that is generated during the impact of the vehicle is applied. On the other hand, disadvantageously, frame components, with which the sensor strain portion and various types of sensor members contact, may deform during or after the impact. The deformation of the frame components unavoidably leads to degradation of sensor functionality.
The present invention has been made in view of the above circumstances, and provides a load detecting device for a vehicle seat restraining load detecting functionality of a seat for a vehicle from degrading when an excessive load generated during impact of the vehicle or similar situations is applied, and maintaining an operational state.